Geological evolution of the northern and northwestern Eastern Ghats Belt, India from metamorphic, structural and geochronological records: An appraisal
Abstract:The Eastern Ghats Belt of India remains a focus of intense research by the international geoscience community to understand the Proterozoic crustal evolution. This terrane experienced anomalous thermal perturbation at least two times in Earth's history and those are linked with the assembly of two Proterozoic supercontinents. It is clearly demonstrated from existing rock records that the terrane experienced multiple events of metamorphism, magmatism, and deformation characterizing separate crustal provinces. D… Show more
“…1 inset) although it was assigned the status of a separate crustal domain. However, recent studies put question marks on this domain-based classification (Ganguly et al , 2018; Ganguly and Chatterjee, 2020). Fig.…”
Orthopyroxene-bearing felsic gneiss occurs as foliation-parallel layers and bands together with aluminous granulite, mafic granulite, and quartzofeldspathic granulite in the Chilka Lake migmatite complex of the Proterozoic Eastern Ghats Belt, India. The rock was classified previously as charnockite which underwent granulite-facies metamorphism. Field and textural features of this rock show evidence of the partial melting of a biotite-bearing greywacke protolith. Orthopyroxene with/without garnet and cordierite were produced with K-feldspar as peritectic phases of incongruent melting of presumed metaluminous sediments. Fluid-inclusion data suggest the presence of high-density CO2-rich fluids during peak metamorphism, which are similar to those found in associated aluminous granulite. Whole-rock major and trace element data show wide variability of the source materials whereas REE distributions show enriched LREE and flat HREE patterns. Zircon grains from representative samples show the presence of inherited cores having spot dates (SHRIMP) in the range c. 1790–3270 Ma. The overgrowth on zircon was formed predominantly during c. 780–730 Ma and sporadically during c. 550–520 Ma. Some neoblastic zircons with c. 780–730 Ma ages are also present. U-rich dark zones surrounding cores appear partially metamictised, but spot ages from this zone vary within c. 1000–900 Ma. The <1000 Ma ages represent metamorphism that mirrors the events in associated aluminous granulite. The sources of metaluminous sediments are speculative as the rock compositions are largely modified under granulite-facies metamorphism and partial melting. Considering the accretionary tectonic setting of the Eastern Ghats Belt during the c. 1000–900 Ma time frame, a greywacke-type protolith for the migmatite complex has been proposed.
“…1 inset) although it was assigned the status of a separate crustal domain. However, recent studies put question marks on this domain-based classification (Ganguly et al , 2018; Ganguly and Chatterjee, 2020). Fig.…”
Orthopyroxene-bearing felsic gneiss occurs as foliation-parallel layers and bands together with aluminous granulite, mafic granulite, and quartzofeldspathic granulite in the Chilka Lake migmatite complex of the Proterozoic Eastern Ghats Belt, India. The rock was classified previously as charnockite which underwent granulite-facies metamorphism. Field and textural features of this rock show evidence of the partial melting of a biotite-bearing greywacke protolith. Orthopyroxene with/without garnet and cordierite were produced with K-feldspar as peritectic phases of incongruent melting of presumed metaluminous sediments. Fluid-inclusion data suggest the presence of high-density CO2-rich fluids during peak metamorphism, which are similar to those found in associated aluminous granulite. Whole-rock major and trace element data show wide variability of the source materials whereas REE distributions show enriched LREE and flat HREE patterns. Zircon grains from representative samples show the presence of inherited cores having spot dates (SHRIMP) in the range c. 1790–3270 Ma. The overgrowth on zircon was formed predominantly during c. 780–730 Ma and sporadically during c. 550–520 Ma. Some neoblastic zircons with c. 780–730 Ma ages are also present. U-rich dark zones surrounding cores appear partially metamictised, but spot ages from this zone vary within c. 1000–900 Ma. The <1000 Ma ages represent metamorphism that mirrors the events in associated aluminous granulite. The sources of metaluminous sediments are speculative as the rock compositions are largely modified under granulite-facies metamorphism and partial melting. Considering the accretionary tectonic setting of the Eastern Ghats Belt during the c. 1000–900 Ma time frame, a greywacke-type protolith for the migmatite complex has been proposed.
“…Kinematics and chronology of these crustal-scale shear zones have been constrained in recent times, such as the KFZ [50], the MSZ [81,91,92], and the RSZ [48]. Structuralcum-metamorphic studies have been attempted from some of the north EGB domains such as the Angul domain [93], the Phulbani domain [48,94,95], the Tikarpara domain [81,92,[96][97][98], and the Khariar domain [99]. However, intradomain correlation of deformation-cum-metamorphic imprints is still unclear for lack of geochronological data from individual domains, hindering reconstruction of the overall structural architecture of the northern EGB as a whole.…”
Section: Northern Egbmentioning
confidence: 99%
“…490 Ma [103]. All these data [48,50,65,80,[94][95][96][99][100][101][102][103] point to establishment of dominant dextral slip kinematics along subparallel shear zones (KFZ, MSZ, and RSZ) at ca. 480-521 Ma within the northern EGB.…”
A number of crustal-scale shear zones have developed along the southern margin of the Singhbhum Craton, in the boundary with the Neoarchean Rengali Province and the Meso-Neoproterozoic Eastern Ghats Belt. The cratonic part, evolved in a suprasubduction zone setting, bears imprints of late Mesoarchean orogenic episode (D1C) at ca. 3.1 Ga with folding and thrust imbrication of the cratonic rocks. The succeeding orogenic imprint is etched in the Neoarchean (~2.8 Ga) with development of the Sukinda thrust along the craton margin and thrust-related deformation of the rocks of the Rengali Province (D2C-D1R). The latter event remobilized cratonic fringe with development of a spectacular E-W trending transpressional belt in the Southern Iron Ore Group rocks cored by the Sukinda ultramafics. In the Eastern Ghats Belt, the major ultrahigh-temperature orogeny took place during the Grenvillian-age (~1.0-0.9 Ga) assembly of the supercontinent Rodinia. This belt eventually got juxtaposed against the expanded Singhbhum Craton in the end-Neoproterozoic time (~0.5 Ga) along the Kerajang Fault Zone. This latter event remobilized a large part of the Rengali Province (D2R) with development of an intraterrane transpressional belt bounded by the Barkot Shear Zone in the north. The northern fringe of the intruding Eastern Ghats Belt developed a complex network of strike-slip fault system under this impact, probably an outcome of tectonic activity along the Kuunga suture, which signifies the joining of greater India with East Antarctica. The present synthesis visualizes early development in the craton through formation of a typical orogenic sequence, imbricated in thrust piles, resulting from a ca. 3.1 Ga orogeny. Further cratonic expansion was achieved via repetitive accretion and remobilization, development of crustal-scale faults and transpressional belts at ca. 2.8 Ga and ca. 0.5 Ga, much in a similar fashion as documented along oblique convergent margins of all ages.
“…The majority of these high-grade rocks are either Palaeo-to Mesoproterozoic (c. 1700-1500 or Neoproterozoic to Late Cambrian (c. 1000-900 and 550-480 Ma) in age (e.g. Eastern Ghats Belt; Central India Tectonic Zone; Aravalli Delhi Mobile Belt; Chotanagpur Gneissic Complex; Bhopalpatnam Granulite Belt; and parts of Southern Granulite Terrane) (reviewed in Dasgupta et al 2013;Mukherjee et al 2019;Chattopadhyay et al 2020;Dey et al 2020;Fareeduddin & Banerjee;2020;Ganguly & Chatterjee, 2020;Santosh, 2020). Other than those, the oldest Mesoarchaean-Palaeoproterozoic (c. 3000-2450 Ma) granulite-facies rocks in India are also reported from the Coorg block (Santosh et al 2015;Amaldev et al 2016), Karimnagar Granulite Belt (Santosh et al 2004;Prakash et al 2017) and the southern end of the Dharwar craton (Northern Granulite Terrane or Salem Block) that continues up to the Palghat-Cauvery Shear System (PCSS) within the Southern Granulite Terrane (SGT) (e.g.…”
In the Palghat–Cauvery Shear/Suture Zone of the Southern Granulite Terrane, the Sittampundi Layered Complex occurs as a mappable unit. The Sittampundi Layered Complex consists of mafic, ultramafic and anorthositic rocks with chromitite layers and has been interpreted as an arc/ophiolite complex that formed in an Archaean suprasubduction zone arc setting. In the Sittampundi Layered Complex, reddish-black metabasites occur as layers or boudins with a rim of amphibolite within anorthosite. The peak metamorphic assemblage of the metabasites is garnet + clinopyroxene + quartz + rutile ± plagioclase ± orthopyroxene, and symplectite consisting of amphibole and plagioclase formed around the garnet during retrograde metamorphism. The protolith of metabasite may have intruded in a suprasubduction zone arc setting during the late Neoarchaean (c. 2540–2520 Ma), and then underwent high-pressure granulite-facies peak metamorphism (900–800 °C and 11–14 kbar) in the early Palaeoproterozoic (c. 2460–2440 Ma), followed by amphibolite-facies metamorphism (550–480 °C and 5.5–4.5 kbar) in the middle Palaeoproterozoic (c. 1900–1850 Ma). The results obtained in this study, together with previous studies, indicate that: (1) the high-pressure granulite-facies metamorphism in the study area indicates that subduction occurred during the Archaean–Proterozoic boundary with a higher apparent average geothermal gradient (∼20–16 °C km−1) than the modern-day Earth, and (2) the apparent average geothermal gradient of the subduction zone was ∼29–14 °C km−1 during the Archaean–Proterozoic boundary, which was still too high to enter the realm of eclogite-facies metamorphism.
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